/**
 * Copyright (C) 2002-2015   The FreeCol Team
 * <p>
 * This file is part of FreeCol.
 * <p>
 * FreeCol is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 2 of the License, or
 * (at your option) any later version.
 * <p>
 * FreeCol is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * <p>
 * You should have received a copy of the GNU General Public License
 * along with FreeCol.  If not, see <http://www.gnu.org/licenses/>.
 */

package net.sf.freecol.server.ai.goal;

import java.util.Iterator;
import java.util.logging.Logger;

import javax.xml.stream.XMLStreamException;

import net.sf.freecol.common.io.FreeColXMLReader;
import net.sf.freecol.common.io.FreeColXMLWriter;
import net.sf.freecol.common.model.PathNode;
import net.sf.freecol.common.model.Tile;
import net.sf.freecol.common.model.Unit.MoveType;
import net.sf.freecol.server.ai.AIPlayer;
import net.sf.freecol.server.ai.AIUnit;


/**
 * A goal to make a move to a tile adjacent to a target tile.
 */
public class GotoAdjacentGoal extends Goal
{

    private static final Logger logger = Logger.getLogger( GotoAdjacentGoal.class.getName( ) );

    //the destination tile
    private final Tile target;

    public GotoAdjacentGoal( AIPlayer p, Goal g, float w, AIUnit u, Tile t )
    {
        super( p, g, w, u );
        target = t;
    }

    @Override
    protected Iterator< AIUnit > getOwnedAIUnitsIterator( )
    {
        //we're keeping units on the availableUnitsList,
        //so all our own units at any moment are these
        return availableUnitsList.iterator( );
    }

    @Override
    protected Iterator< Goal > getSubGoalIterator( )
    {
        return null;
    }

    @Override
    protected void removeUnit( AIUnit u )
    {
        Iterator< AIUnit > uit = availableUnitsList.iterator( );
        while ( uit.hasNext( ) )
        {
            AIUnit unit = uit.next( );
            if ( unit.equals( u ) )
            {
                uit.remove( );
            }
        }
    }

    @Override
    protected void plan( )
    {
        isFinished = false;

        //Run through available units. For each unit, find a path to the
        //target and move towards it. Return to parent if adjacent to target,
        //or no path can be found.
        Iterator< AIUnit > uit = availableUnitsList.iterator( );
        nextUnit:
        while ( uit.hasNext( ) )
        {
            AIUnit u = uit.next( );

            PathNode pathNode = u.getUnit( ).findPath( target );
            if ( pathNode == null )
            {
                uit.remove( );
                addUnitToParent( u );
            }
            else
            {
                while ( pathNode.next != null
                        && pathNode.getTurns( ) == 0
                        && pathNode.getTile( ) != target
                        && ( u.getUnit( ).getMoveType( pathNode.getDirection( ) ) == MoveType.MOVE
                        || u.getUnit( ).getMoveType( pathNode.getDirection( ) ) == MoveType.EXPLORE_LOST_CITY_RUMOUR ) )
                {

                    if ( u.getUnit( ).getMoveType( pathNode.getDirection( ) ) == MoveType.EXPLORE_LOST_CITY_RUMOUR )
                    {
                        logger.warning( "Accidental rumour exploration!" );
                    }

                    u.move( pathNode.getDirection( ) );
                    if ( u.getUnit( ) == null
                            || u.getUnit( ).isDisposed( ) )
                    {
                        continue nextUnit;
                    }
                    pathNode = pathNode.next;
                }
                if ( u.getUnit( ).getTile( ).isAdjacent( target ) )
                {
                    //If unit is adjacent after moving, return to parent
                    uit.remove( );
                    addUnitToParent( u );
                }
            }
        }

        if ( availableUnitsList.isEmpty( ) )
        {
            //we don't have any units left to deal with,
            //signal that we may safely be cancelled now
            isFinished = true;
        }
    }

    @Override
    public String getGoalDescription( )
    {
        String descr = super.getGoalDescription( );
        if ( target != null )
        {
            descr += ":" + target.getX( ) + "," + target.getY( );
        }
        else
        {
            descr += ":null";
        }
        return descr;
    }


    @Override
    public void toXML( FreeColXMLWriter xw ) throws XMLStreamException
    {
    }

    @Override
    public void readFromXML( FreeColXMLReader xr ) throws XMLStreamException
    {
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String getXMLTagName( ) { return getXMLElementTagName( ); }
}
